You can ask this about any thing that is crazy popular but I'm not coming at this from a position of attack. I love FFVII and feel it deserves all the hype. But it still behooves us to analyze these things, I think.

Was it merely a "right time/right place" situation?
Or was there something innate to FFVII's story/characters/mechanics/whatever that set it apart and made it have such a profound impact on video games?